Designers of military aircraft have been, over the years, more and more successful in building aircraft that fly many times the speed of sound and can withstand high "G" forces. When such aircraft enter a sharp turn or climb at these high speeds, as often happens in combat maneuvers, its flightpath forms a curve and the pilot experiences a "G" force higher than one times the force of gravity (also known as 1 G) due to excess acceleration. Although the airframe and engines may continue to perform in very high G manuevers, the tolerance of a pilot seated erectly at the controls is limited to both the duration and severity of the resulting force. The hydrostatic forces on his blood cause it to collect away from the brain, leading to "greyout" or blackout. If cerebral dysfunction, caused by lack of O.sub.2 to the brain, of the pilot were to occur, the result could be catastrophic, to include loss of the pilot and loss of the aircraft, or much worse, loss of life or property on the ground.
One of the better known methods of lessening these effects on the pilot is to wrap his lower body in bladders, otherwise known as "G" suits, that inflate or deflate according to sensors that detect changes in the force of gravity. U.S. Pat. No. 4,243,024 to Richard J. Crosbie et al. shows an example of a gravity protective system that includes a pressurized suit.
Another method and apparatus known in the art is to rotate the pilot's seat, to place him in a supine position during the highest G's, based upon a complicated device that acts to fold the pilot's legs into a tucked position and then rotates the seat about the Z--or vertical axis. One such apparatus is disclosed in U.S. Pat. No. 4,301,983 entitled "High Acceleration Protective Seat" issued to J. J. Horan.
Although these methods, and the apparatus they employ, achieve a limited measure of success in keeping the pilot fully conscious during aerial maneuvers, each has shortcomings. For instance, the disadvantage with such "G" suits is that they fail to deal with the problems of compressive forces exerted on the spine by the "g" forces as well as local pressure points located where the pilot's body contacts the seat. With devices that move the pilot's legs and the seat, extra machinery is necessary and this adds to the overall weight of the aircraft.